EP0932022B1 - Verfahren und Vorrichtung für Dimensionsmessung und Inspektion von Strukturen - Google Patents

Verfahren und Vorrichtung für Dimensionsmessung und Inspektion von Strukturen Download PDF

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Publication number
EP0932022B1
EP0932022B1 EP98101206A EP98101206A EP0932022B1 EP 0932022 B1 EP0932022 B1 EP 0932022B1 EP 98101206 A EP98101206 A EP 98101206A EP 98101206 A EP98101206 A EP 98101206A EP 0932022 B1 EP0932022 B1 EP 0932022B1
Authority
EP
European Patent Office
Prior art keywords
surroundings
removal
etching mask
interesting feature
corpuscular
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP98101206A
Other languages
English (en)
French (fr)
Other versions
EP0932022A1 (de
Inventor
Jürgen Dr. Frosien
Akira Kintaka
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Advantest Corp
Original Assignee
Advantest Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Advantest Corp filed Critical Advantest Corp
Priority to EP98101206A priority Critical patent/EP0932022B1/de
Priority to DE69813500T priority patent/DE69813500T2/de
Priority to US09/189,832 priority patent/US6093512A/en
Priority to JP10339905A priority patent/JPH11223522A/ja
Publication of EP0932022A1 publication Critical patent/EP0932022A1/de
Application granted granted Critical
Publication of EP0932022B1 publication Critical patent/EP0932022B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/30—Electron-beam or ion-beam tubes for localised treatment of objects
    • H01J37/305—Electron-beam or ion-beam tubes for localised treatment of objects for casting, melting, evaporating or etching
    • H01J37/3053—Electron-beam or ion-beam tubes for localised treatment of objects for casting, melting, evaporating or etching for evaporating or etching
    • H01J37/3056—Electron-beam or ion-beam tubes for localised treatment of objects for casting, melting, evaporating or etching for evaporating or etching for microworking, e.g. etching of gratings, trimming of electrical components
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B15/00—Measuring arrangements characterised by the use of electromagnetic waves or particle radiation, e.g. by the use of microwaves, X-rays, gamma rays or electrons
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
    • G01N23/22—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material
    • G01N23/225—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material using electron or ion
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/26—Electron or ion microscopes
    • H01J2237/28—Scanning microscopes
    • H01J2237/2813—Scanning microscopes characterised by the application
    • H01J2237/2814—Measurement of surface topography

Definitions

  • the invention relates to a method for dimension measurement and inspection of structures having a high aspect ratio according to the preamble to claim 1. Furthermore, this invention is directed to an apparatus for dimension measurement and inspection of these structures according to the preamble to claim 14.
  • the reason for this invisibility is the secondary electrons released by the primary electron beam, which are difficult to detect.
  • post-lens detection systems where the detector is arranged between the probe and the lens, the secondary electrons cannot be extracted from the bottom of the structure.
  • In-lens or pre-lens detection systems where the detector is arranged in or in front of the lens, use a high secondary electron attraction field causing the secondary electrons from the bottom of the structure to occupy only a small angle close to the optical axis and to move up the scanning electron microscope column in the direction of the cathode. Since the secondary electrons are extracted and accelerated, they behave very much like the primary electron beam and, therefore, are difficult to detect. Additionally, surface charging can influence the emission and detection of the secondary electrons.
  • Backscattered electrons and accelerated secondary electrons are, as mentioned, difficult to detect and require additional elements with consequent limitation of resolution.
  • Artificial surface charging also causes disturbances of the primary beam and consequently causes measurement errors or limitations.
  • U.S. 5,594,245 relates to an apparatus and a method of observing surface configurations, especially configurations of the bottom of a deep hole, by using an electron beam.
  • the primary electron beams has sufficiently high energy to allow reflection electrons to penetrate through the side wall of the hole.
  • the invention is characterized in that surroundings of the interesting feature are removed before measurement and inspection thereof in order to increase the detection efficiency.
  • a corpuscular induced etching technique is used for the removal of the surroundings.
  • Fig.1 shows an apparatus for dimension measurement and inspection of a structure 1, with which a focused corpuscular beam 2, e.g. an electron beam or an ion beam, can be generated in an optical column 3.
  • a focused corpuscular beam 2 e.g. an electron beam or an ion beam
  • the column 3 essentially comprises means 4 for generating the corpuscular beam 2, an objective lens 5 for focusing the corpuscular beam onto the structure 1 and a detector 6 for detecting the backscattered electrons and/or the secondary electrons released by the focused corpuscular beam.
  • a blanking system 7 and a deflection system 8 are provided.
  • the corpuscular beam 2 generated by the means 4 is focused on the structure 1 through the objective lens 5.
  • the backscattered and/or secondary electrons 9 released from the bottom of the structure 1 move upwards the optical column close to its optical axis and therefore, are difficult to detect by the detector 6.
  • Fig.2 Apparatus for dimension measurement and inspection of structures having a high aspect ratio according to a second embodiment of the invention is illustrated in Fig.2. While Fig.1 shows a post-lens detection arrangement, Fig.2 discloses a pre-lens detection arrangement. Accordingly, the detector 6' is arranged between the means 4 for generating the corpuscular beam and the objective lens 5. Furthermore, an acceleration electrode 10 is provided to help the backscattered and secondary electrons to pass through the objective lens 5. However, the accelerated backscattered and secondary electrons 9 then behave very much like the primary beam and therefore they are difficult to detect.
  • Figs.3a and 3b show a structure representing a contact hole.
  • the interesting feature of this structure is, for instance, the diameter at the bottom of this hole.
  • the method according to the invention proposes to remove surroundings of the interesting feature before its measurement and inspection.
  • an image is advantageously made from the structure, e.g. by scanning it with the help of the corpuscular beam 2.
  • etching mask 11 for the structure according to Figs.3a and 3b is illustrated in Fig.4.
  • the etching mask comprises a round element 11a which has the same diameter as the contact hole 12 of the structure. Furthermore, the mask 11 defines a rectangular window 11b surrounding the round element 11a.
  • the apparatus according to Fig.1 or Fig.2 further comprises means for removal of surroundings of the interesting feature to increase the detection efficiency.
  • These means can be defined by means 4 for generating the corpuscular beam.
  • another possibility is to provide an additional means 13 for removal of surroundings of the interesting feature which are placed within the optical column 3.
  • a corpuscular induced etching technique is used for the removal of the surroundings.
  • an ion beam or an electron beam can be used.
  • the means for removal of the surroundings can also comprise means 14 for supplying a gas in the region of the structure 1 to assist the beam in removing the surroundings. Therefore, it is possible to use a gas-assisted ion beam or a gas-assisted electron beam or even a gas-assisted light beam for the removal of the surroundings.
  • the same corpuscular beam is used for the measurement and inspection as well as for the removal of the surroundings.
  • an additional source 13 within or outside the optical column 3 can also be applied.
  • the mask 11 avoids damage to the interesting feature and restricts the area in which the material is to be removed.
  • Figs.5a and 5b show the structure according to Figs.3a and 3b after the removal of the surroundings.
  • the surroundings were removed to a certain depth 1, thereby decreasing the aspect ratio.
  • the removal of the surroundings enables the escape of the secondary electrons and backscattered electrons or other corpuscles as can be seen by Fig.5b in comparison with Fig.3b. Consequently, the imaging and high-precision critical dimension measurement is improved.
  • etching mask according to Fig.4 can also be made slightly larger than the structure in order to avoid damage to the interesting feature.
  • Fig.6 discloses such an etching mask 11'. Its round element 11'a has a diameter which is slightly larger than the inner diameter of the contact hole 12. In this case, a thin cylindrical wall 12a surrounding the feature is the result of the removal of the surroundings. Using such a solution, the secondary electrons generated by the backscattered electrons at the outer wall of the cylinder are used for signal detection in addition to the secondary electrons which can escape directly.
  • Figs.8a and 8b disclose another structure 13 which is to be inspected. This structure defines a thin groove.
  • etching mask 12'' is generated which avoids damage to an interesting feature 16.
  • the etching mask 12'' defines a rectangular window which partially overlaps the structure 13.
  • the material is removed to a certain depth, e.g. half the depth of the groove as shown in Fig.10a or the full depth of the groove as shown in Fig.10b.
  • Fig.10c is a top view of the structure after the removal of surrounding material which was defined by the mask 12''. This technique opens the groove on one of its sides and, therefore, opens gateways for the backscattered and secondary corpuscles.
  • Fig.8a discloses an angular area 17 of corpuscle detection which is limited by the structure. Due to the removal of the surroundings, Fig.10c shows an improved angular area 17' of corpuscle detection.
  • the proposed methods and apparatus can be fully automated. Consequently, the critical dimension measurement and inspection can be undertaken without operator support.
  • Known techniques like automatic navigation to measurement location, automatic setting of focus and beam parameter and automatic image acquisition can be used.
  • the critical dimension data and the condition of the top layer can be determined using state of the art technology.
  • the etching mask can be generated automatically from the top image data. Use of layout data can support this step. However, in some cases it may be preferable to generate the etching mask manually.
  • the generation of the etching mask and the removal of the material can be performed and controlled either by system parameter pre-settings or by using the contrast of the secondary and/or backscattered corpuscle signal.
  • secondary electron and/or backscattered electron signals will be used, but also secondary and/or backscattered ion signals are possible.
  • the etching masks will be generated virtually, and consequently, means 4 for generating the corpuscular beam and the blanking system 7 are supplied with control signals to generate a corpuscular beam on the structure corresponding to the etching mask.
  • an apparatus can be used.
  • a high-resolution (low-energy) secondary electron microscope is preferred having means 4 for generating an electron beam which is defined by a cold, thermal or photocathode electron source.
  • the apparatus preferably has a blanking system 7 for electron dose control.
  • components to increase spatial resolution and/or increase probe current such as aberration correction elements (e.g. multipole corrector), monochromators, can preferably be integrated.
  • a high-resolution focused ion beam apparatus having a liquid metal ion, a gaseous or another high-brightness ion source can be used.
  • a combination of a secondary electron microscope and a focused ion beam apparatus according to the above-mentioned features.
  • the apparatus should preferably have means for carrying out gas-assisted material removal techniques, e.g. one or more nozzles 14 for supplying suitable gases close to the corpuscular beam (cf. Fig.2).
  • etching masks to increase signal detection will depend on feature shape, measurement task and other requirements.
  • the orientation of the etching masks is selected according to the position of the detector or detectors to obtain maximum signal detection efficiency.
  • the orientation of the etching masks may also be chosen in such a way that optimum contrast effects (e.g. for special topography details) can be generated.

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  • Physics & Mathematics (AREA)
  • Analytical Chemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Electromagnetism (AREA)
  • Plasma & Fusion (AREA)
  • Health & Medical Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Preparing Plates And Mask In Photomechanical Process (AREA)
  • Length-Measuring Devices Using Wave Or Particle Radiation (AREA)
  • Analysing Materials By The Use Of Radiation (AREA)

Claims (14)

  1. Verfahren zur kritischen Dimensionsmessung und Inspektion von Strukturen mit einem hohen Seitenverhältnis, wobei ein Korpuskularstrahl auf ein interessierendes Element der Struktur gerichtet wird und durch den Korpuskularstrahl ausgelöste Rückstreukorpuskel und/oder Sekundärkorpuskel nachgewiesen und bewertet werden,
    dadurch gekennzeichnet, dass vor der Messung und Inspektion die Umgebung des interessierenden Elements entfernt wird, um den Wirkungsgrad des Nachweises zu erhöhen, wobei eine Korpuskularstrahl unterstützte Ätztechnik zur Entfernung der Umgebung verwendet wird und eine Ätzmaske vor dem Entfernen der Umgebung zur Vermeidung eines Schadens an dem interessierenden Element erzeugt wird.
  2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass die Ätzmaske manuell erzeugt wird.
  3. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass die Ätzmaske automatisch aus einem abgetasteten Bild eines Bereichs, welcher die Struktur enthält, erzeugt wird.
  4. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass die Umgebung des interessierenden Elements bis zu einer bestimmten Tiefe entfernt wird, um das Seitenverhältnis zu verringern.
  5. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass die Ätzmaske die Struktur teilweise überlappt, um Passagen für die Rückstreu- und Sekundärkorpuskel zu öffnen.
  6. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass die Ausrichtung der Ätzmaske in Abhängigkeit der Position des Detektors ausgewählt wird.
  7. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass ein Ionenstrahl zur Entfernung der Umgebung verwendet wird.
  8. Verfahren nach Anspruch1, dadurch gekennzeichnet, dass ein gasunterstützter Ionenstrahl zur Entfernung der Umgebung verwendet wird.
  9. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass ein gasunterstützter Elektronenstrahl zur Entfernung der Umgebung verwendet wird.
  10. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass ein gasunterstützter Lichtstrahl zur Entfernung der Umgebung verwendet wird.
  11. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass der selbe Korpuskularstrahl zur Entfernung der Umgebung verwendet wird.
  12. Vorrichtung zur Messung und Inspektion kritischer Abmessungen von Strukturen mit einem hohen Seitenverhältnis, enthaltend
    Mittel (4) zur Erzeugung eines auf ein interessierendes Element der Struktur (1) gerichteten Korpuskularstrahls (2),
    Detektormittel zum Nachweis von durch den Korpuskularstrahl ausgelösten Rückstreu- und Sekundärelektronen (9),
    gekennzeichnet durch
    Mittel zum Entfernen der Umgebung des interessierenden Elements 1 zur Erhöhung des Nachweiswirkungsgrades und
    Mittel zur Erzeugung einer Ätzmaske (11) zur Entfernung der Umgebung, die einen Schaden an dem interessierenden Element verhindert.
  13. Vorrichtung nach Anspruch 12, dadurch gekennzeichnet, dass die Mittel zur Entfernung der Umgebung Mittel zur Erzeugung eines Korpuskularstrahls und Mittel zur Beaufschlagung eines Gases im Bereich des Korpuskularstrahl aufweisen.
  14. Vorrichtung nach Anspruch 12, dadurch gekennzeichnet, dass die Mittel zur Entfernung der Umgebung Mittel zur Erzeugung einer virtuellen Ätzmaske enthalten.
EP98101206A 1998-01-23 1998-01-23 Verfahren und Vorrichtung für Dimensionsmessung und Inspektion von Strukturen Expired - Lifetime EP0932022B1 (de)

Priority Applications (4)

Application Number Priority Date Filing Date Title
EP98101206A EP0932022B1 (de) 1998-01-23 1998-01-23 Verfahren und Vorrichtung für Dimensionsmessung und Inspektion von Strukturen
DE69813500T DE69813500T2 (de) 1998-01-23 1998-01-23 Verfahren und Vorrichtung für Dimensionsmessung und Inspektion von Strukturen
US09/189,832 US6093512A (en) 1998-01-23 1998-11-10 Method and apparatus for dimension measurement and inspection of structures utilizing corpuscular beam
JP10339905A JPH11223522A (ja) 1998-01-23 1998-11-30 構造物の寸法測定及び検査のための方法及び装置

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP98101206A EP0932022B1 (de) 1998-01-23 1998-01-23 Verfahren und Vorrichtung für Dimensionsmessung und Inspektion von Strukturen

Publications (2)

Publication Number Publication Date
EP0932022A1 EP0932022A1 (de) 1999-07-28
EP0932022B1 true EP0932022B1 (de) 2003-04-16

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EP98101206A Expired - Lifetime EP0932022B1 (de) 1998-01-23 1998-01-23 Verfahren und Vorrichtung für Dimensionsmessung und Inspektion von Strukturen

Country Status (4)

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US (1) US6093512A (de)
EP (1) EP0932022B1 (de)
JP (1) JPH11223522A (de)
DE (1) DE69813500T2 (de)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7388218B2 (en) * 2005-04-04 2008-06-17 Fei Company Subsurface imaging using an electron beam

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5594245A (en) * 1990-10-12 1997-01-14 Hitachi, Ltd. Scanning electron microscope and method for dimension measuring by using the same
US5741614A (en) * 1995-10-16 1998-04-21 Nikon Corporation Atomic force microscope measurement process for dense photoresist patterns

Also Published As

Publication number Publication date
DE69813500T2 (de) 2004-02-19
EP0932022A1 (de) 1999-07-28
DE69813500D1 (de) 2003-05-22
US6093512A (en) 2000-07-25
JPH11223522A (ja) 1999-08-17

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